97 Boniville Engine warms up then hard to start

I have a 97 Pontiac Boniville that when i start i can drive it all day until the engine warms up and then it when i park it and come back to start it up later it will crank. I have to let the engine cool off so i can start the car backup and drive it. I already replaced the ignition modual on the car. Does anyone here have an idea on what is causing it to not start when the engine is hot?

More than likely the crank position sensor (CKPS) has become heat sensitive. I would replace it.